STEP 1:

Assess synoptic situation for weak convergence near a trough line or a low.  Also look for over running from a system south of the forecast area.

Here is the 12Z 28JAN02 ETA model run for 00Z 29JAN02.

Compare this to what the ETA model showed for 06Z 29JAN04

Take a look at what the same model was showing for 18Z 28JAN02